In the process of manufacturing a semiconductor device, a substrate, such as a wafer, is subjected to various kinds of processes. One example of such processes may include a process of forming a film using an alternate supplying method. The alternate supplying method used herein refers to a method of alternately supplying at least two kinds of process gases including a precursor gas and a reaction gas reacting with the precursor gas onto a substrate to be processed, forming layers one by one by reacting these gases on a surface of the substrate, and forming a film of a desired thickness by stacking each of the layers.
One type of substrate processing apparatus, which performs the process of forming the film using the alternate supplying method, may include the following configuration. This type of substrate processing apparatus may include a processing chamber partitioned into a first processing region having a first processing gas atmosphere, a second processing region having a second processing gas atmosphere, and a purge region interposed between the first and the second processing regions for separating these gas atmospheres from each other. A substrate mounting table is moved into the processing chamber and then, a substrate on the substrate mounting table is allowed to pass through each region so that a film forming process is performed on the substrate.
However, in the above-described conventional substrate processing apparatus, gases may not be always uniformly supplied onto the substrate to be processed with a high level of exposure. For example, when the gases are, in one region, supplied from one end of the region and is exhausted through the other end, even though the exposure level of the gases on the plane of the substrate is sufficient at the one end, it may be insufficient at the other end. In addition, if an attempt is made to secure a sufficient exposure level of gases to the substrate, a throughput of the film forming process may be likely to be decreased. For example, in each region, if an upper space of the substrate is spacious, the gases may be diffused due to the spacious area, which may result in difficulty in securing a high gas flow velocity. Further, it may take a long time to spread the gases throughout the surface of the substrate or to supply or exhaust the gases into or from the region.